1. Field of the Invention
The present invention relates to an optical film and a digital pen system using the same, and more particularly, to a high-luminance optical film attached on a display and a digital pen system providing positional information using the same.
2. Discussion of Related Art
A digital pen system is a pen of a new concept in which analog and digital methods are combined. When characters are written on a paper as is done by a general pen, the written content is stored in a memory built in the digital pen, which is then transferred in the form of an image file to a computer for management. Although documents written by the general pen can also be scanned by a scanner (electronic color analysis machine) and stored in the form of the image file, the digital pen has advantages in that the documents written by the digital pen do not need to be scanned and can be easily managed using a separate program. The digital pen developed in an early stage could be used only when it was connected to a computer. In other words, in order to use the digital pen, the computer should always be turned on and the digital pen should be used only near the computer. In addition, in a case of storing the content in the computer, the resolution of the image file was poor so that the content could not be exactly recognized.
In recent years, a high-performance digital pen in which the written content can be stored in the memory built in the digital pen and converted to digital data at any time when it is connected to a computer has also been released. Further, not only digital pens in which liquid crystal displays are built and the content being written is allowed to be directly checked on screens but also digital pens that can wirelessly transfer data without being connected to a cable have been developed, and touch-screen schemes that allow positional information of the digital pen on the display to be sensed or techniques that allow moving trajectories of the digital pen to be sensed using an externally mounted sensor have been employed.
In order to use the digital pen, a transparent film in which dot patterns are implemented should have a property for scattering infrared rays. However, since the transparent film scatters visible rays as well as infrared rays, it has a problem in that an image is distorted and the visibility is deteriorated to cause a display to be dim when the transparent film is attached on the display.
A technique for sensing touch positions of the digital pen and displaying graphical information at the sensed positions using an infrared ray sensor mounted on the digital pen is disclosed in various documents including Korean Patent Publication No. 10-2010-0134331. However, according to the disclosed document mentioned above, an optical film is formed of a material that can reflect infrared and visible rays so that the digital pen can recognize marks on the optical film. When this optical film is attached to the display, there arises a problem in that the definition and the visibility of the overall image are deteriorated.